Hydraulic brake system



Feb. 1, 1938. w, F, IVER 2,106,757

HYDRAULIC BRAKE SYSTEM Filed Feb. 28, 1934 2 Sheets-Sheet 1 /40 I F 25. Z- I INVENTOR.

WQLLGCE F OLA/5 ATTORNEYj' Feb. 1, 1938. w. F. OLIVER HYDRAULIC BRAKE SYSTEM Filed Feb. 28, 1934 2 Sheets-Sheet 2 INVENTOR. W041. (-765 04 /1/ e BYWM :4 My ATTORNEYJ' Patented res. ll, i938 I 2,186,757 RAULKC BRAKE SYS Wallace F. Oliver, Detroit, Mich, assignor to Hydraulic Brake Company, Detroit, Mich, a corporation of California Application February 28, 1934, Serial No. 713,258

9 Claims. (or. 188-152) g creating an initial pressure in the system for moving the friction elements of the brake into drum engagement.

A further object of theinvention is to provide a hydraulic-brake system including means for actuating a plurality of brakes wherein of the y brakes the greater part of the effect at the-brakes will be-derived from manually applied pressure.

Other objects of the invention will appear from the following description taken in connection with the drawings which form a part of this specification, and in which,---

Figure l is a diagrammatical illustration of a motor vehicle equipped with a hydraulic brake system embodying the invention;

Figure 2 is an enlarged detail view of a valve structure, and v Figure 3 is an enlarged viewof a compression device.

Referring to the drawings for more specific details of the invention, I8 represents a crossmember of a motor vehicle chassis frame. The cross-member has secured thereon a compression device I2 including a reservoir I4 having a filling opening I8 closed as by a plug I8, and formed on one side of the reservoir is an annular shoulder 28.

In the bottom of the reservoir, concentrically disposed to the annular shoulder 28, is a cylinder 22 having a port 24 providing a communication 5 between the cylinder and the reservoir, and arranged below the cylinder 22 is a cylinder 26 having ports 28 and 38 providing communications between the cylinders 22 and 26 and a discharge port 32. The cylinder 26 also has a drain'opening 34 closed as by a plug 36, 'the inner end of which extends into the cylinder, the purpose of which will hereinafter appear.

The discharge port 82 of the cylinder. 26 has connected thereto a conduit 38 communicating with branch conduits 48 and 82, which communicate respectively with conduits 44 and 48 having their respective ends connected to expansible elements or motor cylinders 48 of conventional type.

The motor cylinders 48 are connected between the separable ends of friction elements 58 and 52,

arranged for cooperation with rotatable drums 5%, which may be suitably secured to the wheels of a vehicle, and the respective pairs of friction elements 58 and 52 are connected by retractable springs 56.

The cylinder 26 has therein-apiston 58. As shown, the body of, this piston is reduced in crosssection to provide an annular chamber 88 between the piston and the wall of the cylinder. This chambercommunicates with the cylinder 22 by way of the port 38, and the head of the piston 58 has a plurality of openings 82 providing communications between the chamber 88 and that portion of the cylinder chamberforward. of the head of the piston 58, and positioned on the head of the piston is a collapsible leak-proof cup 84 held against displacement by a spring 68 interposed between the cup 84 and the head 'of the cylinder. The spring 85 also serves to return the piston to its retracted position, in which position the pistonis seated on the plug 88.

The skirt of the piston 58 hasa circumferential groove 88 in which is seated a leak-proof washer I8, and formed in the backof the piston is a recess I2 receiving the free end of a. thrust rod l4, the other end of which is pivotally connected to an arm I8 keyed on a shaft I8 journaled'in a bracket 88 on the cross-member I8, andsuitably secured to the shaft is a' foot pedal level-=82 extending through an opening in a foot-board 84 of the body of the vehicle. The foot pedal lever is returned to its retracted or normal position by a retractor spring 88 connecting the pedal to a fixed support 88.

Suitably secured on the annular shoulder 28 is a cylinder. 98, the head of which is provided with an opening arranged concentrically to the cylincompression spring I88. The enlarged portion I88 onthe rod I82 has a bore H8 in which is secured a piston rod I I2. The piston rod extends through a packing box I I4 threaded in the cylinder 22 and provided with a leak-proof cup II6,

' suitably secured against displacement, and formed on the rod H2 is a piston II8 fitted in the cylinder 22.

The body portion of the piston H8 is reduced in cross-section to provide a chamber I20 communicating by way of the port 24 with the reservoir I4, and the head of the piston has a plurality is secured to a bracket I30 attached to the foot board 84, and a wire I3 in the casing has one end secured to the rod I02 and its other end sup-' ported on the bracket I30 and provided with a catch I34 cooperating with a spring-pressed latch I36 on the pedal 82.

The cylinder has a port I38 connected by a conduit I40 to a valve I having a chamber I42 vented as at I44, and a spring-pressed valve I46 in the chamber I42 has an adjustable stud I46 normally engaged by the foot pedal lever 82 to retain the valve in open position when the foot pedal lever is in normal position, and a conduit I50 connects the valve chamber I42 to an intake manifold I52 of the prime mover of the vehicle.

In operation, assuming that the system is filled with suitable fluid, upon the initial movement of the foot pedal lever 82 tending to apply the brakes, the catch I36 on the lever releases the latch I34 of the Bowden mechanism or wire I32, and, simultaneously therewith, this movement of the lever releases the valve I46 and the valve is urged to its seat, resulting in opening the cylinder 90 to atmosphere.

Upon release of the Bowden mechanism or wire I32 and the valve I46, the spring I08 actuates the piston I 06, and this movement of the piston I06 is transmitted to the piston I I8 resulting in discharging the fluid in the cylinder 22 through ports 28 and 30, past the collapsible cup 64, into cylinder 26, and through the cylinder 26 and discharge port 32 and conduits connected thereto into the expansible elements or motor cylinder 48, resulting in spreading the friction elements-50 and 52 to take up any clearance between the friction elements and the drums 54.

During this movement of the piston IIB, the arm "on the shaft 18 is rocked through anangle by the foot pedal lever 82, and this movement of the arm 16 is transmitted to the rod 14 to take up any slack between the foot pedal lever and the piston 58 and to apply force to the piston 58;

Upon further movement of the foot pedal lever to apply the brakes, the piston 58 is moved on its compression stroke resulting in closing the port 28\ and discharging the fluid in the cylinder 58 through thedischarge port 32 and the conduits and branch conduits connected thereto into the expansible elements or motor cylinders 48,'resulting in spreading the friction elements 50 and 52 into engagement with the drums for effective braking action.

Upon release of the foot pedal lever 82, the retractor spring 86 returns the foot pedal lever to its normal position. During this movement of the foot pedal lever the valve I46 is moved to open position. Upon opening the valve I46, the cylinder 90 is closed to atmosphere and connected to the manifold I52 of the prime mover, resulting in evacuation of the cylinder 90.

As the cylinder 90 is evacuated, the piston I06 is retracted, and compresses the spring I08, and since the piston I06 carries with it the piston 'I I8,

the piston I I8 is alsoretracted. As the piston I I8. moves to its retracted position the Bowden wire I32 moves with the piston and slides in the housing I28. The upper end of the wire is attached to the catch I34, and at the time the piston starts to return, the catch I34 is disengaged from the latch I36 and is to the left of the position shown in Figure 1, As the piston II8 returns and the Bowden wire I32 moves with it, the catch I34 moves to the right as viewed in Figure l, and as .it so moves it slides over the. inclined left-hand end of the catch I36, thereby depressing it until the catch I34 moves past the upwardly projecting linger of the-latch I36, whereupon the latch I36 is-moved upwardly by its spring and the finger of the latch I36 engages the downwardly projecting finger of the catch I34. this mechanism'is' to prevent movement of the piston I I8 when the prime mover is idle.

As the piston II8 moves to its retracted position, the collapsible cup I24 moves from its seat on the'piston H8 and opens the ports I22, resulting in relieving pressure in the cylinder 22 and establishing a free circulation for the fluid between the reservoir and the cylinder 22. When the foot pedal lever moves to its retracted or normal position, the applied force on the piston 58 is released with the result that this piston is moved to its retracted position by the fluid returning from the expansible elements or motor cylinders 48, due to pressure imposed by the retractor springs 56 connected between the friction elements of the respective brake structures, and this movement of the-piston 58 is augmented by thespring 66.

Due tofriction on the 'column of fluid in the cylinder 26 and the conduits connecting this cylinder to the expansible elements or motor cylinders 48, and to the tension of the springs 66, the piston 58 returns to its retracted position slightly in advance of the return of the fluid to the cylinder 26. This causes a partial vacuum in the cylinder 26, resulting in collapse of the cup 64 and admission of fluid from the cylinder 22 supplied from the reservoir through port 24.

Upon complete, return of the piston 58 to its retracted position, the port 28 is uncovered, whereupon further pressure in the cylinder 26 causes the cup 64 to return to its normal or static condition, and any excess fluid returned to the cylinder 26 from the expansible elements or motor cylinders 48 passes from the cylinder 26 The purpose of Having thus described the various features of the invention, what I'claim as new and desire to, secure by Letters Patent is:

1. A hydraulic brake system comprising a primary means for producing pressure in the system, a secondary means for producing pressure connected to the system through the primary 75 means, a source of a predetermined quantity of stored energy for actuating the secondary means, said predetermined quantity being just suflicient to remove slack from the system, means for releasing the stored energy, and means for actuating the primary means including means controlling the release means.

2. A hydraulic brake system comprising a primary means for producing pressure in the system, a secondary mean or producing pressure connected to the system through the primary means, a source of a predetermined quantity of energy for actuating the secondary means, said predetermined quantity being just sufiicient to remove slack from the system, control means for the stored energy, and means for actuating the primary means-including means for releasing the control means.

3. A hydraulic brake system comprising a priexpansible element, a source of a predetermined quantity of stored energy for actuating the secondary means, said predetermined quantity being just suflicient to remove slack from the system, means for restraining the stored energy, and means for actuating the primary means including means for releasing the restraining means.

4. A hydraulic brake system comprising a primary means for producing pressure, an expansible element connected thereto, a brake element operated by the expansible element, a secondary means for producing pressure connected to the expansible means, a compression member for actuating the secondary means, compression means for the member, means for retaining the member under compression, and means for actuating the primary means including means controlling the restraining means.

5. A hydraulic brake system comprising a primary means for producing a pressure, an expansible element connected thereto, a brake element operated by the expansible element, a secondary means for producing pressure connected to the expansible element, expansible means for actuating the secondary means, vacuum means for compressing the expansible means, means for retaining the expansible means under compression, and means for actuating the primary means including means controlling the retaining means.

6. A hydraulic brake system comprising a compression device including a reservoir, a cylinder having aport providing communication between the reservoir and the cylinder, a piston recipro cable in the cylinder, a vacuum chamber, a spring-pressed plunger therein connected to the piston in the cylinder, a second cylinder having ports providing communications between the cylinders, and a piston reciprocable in the second cylinder.

7. A hydraulic brake system comprising a com-- I pression device including a reservoir, a cylinder having a port providing a communication between the reservoir and the cylinder, a piston reciprocable therein, a collapsible leak-proof cup on the head of the piston, a vacuum chamber associated with the cylinder, 2. spring-pressed piston in the vacuum chamber connected to the piston in the cylinder, a second cylinder associated with the first-mentioned cylinderhaving ports providing communications between the cylinders, a piston reciprocable in the second cylinder, a collapsible leak-proof cup on the head of the piston in the second cylinder, and means for actuating the piston in the second cylinder.

8. A hydraulic brake system for motor vehicles having an internal combustion engine comprising a primary means for producing pressure, an expansible element connected thereto, a brake element operated by the expansible element, a secondary means for producing pressure connected to the expansible element, a vacuum chamber, a spring-pressed piston therein connected to the secondary means, a conduit connecting the vac-' uum chamber to' the intake manifold of the engine, means restraining movement of the piston in the vacuum chamber, and means for actuating the primary means including means controlling the restraining means. a

9. A hydraulic brake system for a motor vehicle having an internal combustion engine comprising a primary means for producing pressure, an expansible element connected thereto, a brake element operated by the expansible element, a secondary means'for producing pressure connected to the expansible element through the primary means, a vacuum chamber, a spring-pressed piston in the chamber connected to the secondary means, a conduit connecting the vacuum chamher to the intake manifold of the engine, a valve connected in the conduit, restraining means for the piston in the vacuum chamber, and means for actuating the primary means including means cooperating with the restraining means to release the piston in the vacuum chamber upon initial movement of the actuating means for the primary means. WALLACE F. OLIVER. 

